Debt and Other Obligations (Tables)

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Schedule of long-term debt instruments

Long-term debt is comprised of the following:        

	As of December 31,				Year Ended December 31,
	2015		2014		2015		2014
	(in millions)				(weighted-average interest rates)
Senior Term Loans due through 2027	$	484.2	$	132.0	4.10	%	4.26	%
Junior Term Loans due through 2022	54.3		16.0		6.90	%	6.94	%
Class A enhanced equipment trust certificates due through 2028	95.8		—		4.03	%	N/A
Class B enhanced equipment trust certificates due through 2024	25.0		—		4.37	%	N/A
Long-term debt	$	659.3	$	148.0
Less current maturities	49.6		10.4
Less unamortized discount, net	13.0		2.4
Total	$	596.7	$	135.2

Schedule of maturities of long-term debt

At December 31, 2015, long-term debt principal payments for the next five years and thereafter are as follows:

	December 31, 2015
	(in millions)
2016	$	51.5
2017	49.0
2018	53.0
2019	54.2
2020	54.9
2021 and thereafter	396.7
Total debt principal payments	$	659.3

Schedule of interest expense on long-term debt

Interest expense related to long-term debt consists of the following:

	Year Ended December 31,
	2015		2014
	(in thousands)
Senior term loans	$	15,429	$	738
Junior term loans	2,997		145
Class A enhanced equipment trust certificates	494		—
Class B enhanced equipment trust certificates	140		—
Commitment fees	54		685
Amortization of deferred financing costs	1,165		9
Total	$	20,279	$	1,577